1. Field of the Invention
The present invention relates to systems for charging pressurized cylinders, and more particularly, to a system and method for safely delivering a controlled quantity nitrous oxide gas/liquid to cylinders used to pressurize a device for dispensing food under pressure.
2. Description of Related Art
Numerous compositions to be dispensed as foams, liquids or mixtures have been packaged in pressurized containers. Exemplary compositions include shaving creams and lathers, floor and automobile cleaning and polishing compositions, and food products such as cheese spreads, mayonnaise, whipped cream and the like. In the food industry, pressurized dispensers include either a pressurized aerosol can which holds both the food product and a propellant, or in a two-piece arrangement including a refillable food product storage container connected to a separate, replaceable, miniature gas/liquid propellant bottle, or cylinder. Both of these arrangements have been applied, together with the use of nitrous oxide, to the pressure dispensing of whipped cream food products, for example. The nitrous oxide propellant is stored in gaseous or liquid/gas form in the miniature cylinder.
Both the aerosol can and miniature gas cylinder component of the two-piece arrangement are non-refillable consumables, which present disadvantages in terms of both replacement cost and disposal. The accumulated cost of the disposable pressurized container can be substantial relative to the value of the delivered food product. Used aerosol containers and miniature pressurized cylinders may contain residual gas/liquid pressure and as a result, can be hazardous when crushed or exposed to elevated temperatures. Moreover, improper use and abuse of nitrous oxide is a health hazard, and miniature cylinders filled with that particular gas/liquid have been known to be attractive to both youth and adults, with deleterious effects resulting from inhalation of the gas.
Accordingly, there is a need for a delivery system configured for safe delivery of a predetermined amount of pressurized gas/liquid to a refillable dispensing device. The gas/liquid delivery system needs to be safe and easy to operate and configured both to avoid unintended discharge outside a dispensing device and to prevent overpressurization of the dispensing device and unauthorized access to substantial quantities of the gas/liquid.
The above and other needs are obtained by providing a gas/liquid transfer device for safely delivering a controlled quantity of gas/liquid to a hand held dispensing device. The transfer device includes a fixed volume chamber and a timing mechanism for controlling the transfer from a storage cylinder to the chamber of a predetermined volume of the gas/liquid. The fixed volume chamber is in fluid connection with a filling valve disposed upstream of the chamber and an emptying valve downstream of the chamber. Actuation of both valves is controlled by the timing mechanism, which controls the amount of time the valves are opened. A discharge connector disposed downstream of the emptying valve is arranged to be operatively coupled by an operator to a hand held dispensing device.
In operation, and after being initially charged with a quantity of gas/liquid, the gas/liquid transfer device of the present invention can be activated to deliver a predetermined volume of gas to an attached dispensing device. Upon completion of the transfer, as determined by the timer, the transfer device automatically seals the emptying valve and opens the filling valve to accept a new charge of gas/liquid from the supply cylinder. The duration of time, as controlled by the timer, is sufficient to fill the fixed volume chamber. Each filled dispensing device can be disconnected and replaced by another empty dispensing device, as desired.
The gas/liquid transfer device of the present invention includes safety features directed to prevention of the misuse of, and unauthorized access to, the gas/liquid dispensed by the device. To that end, a predetermined time interval is imposed by the timer between successive transfers of the gas/liquid, thereby preventing access to substantially continuous volumes of dispensed gas/liquid. This problem is also obviated by arranging the timing of the filling and emptying valves to prevent discharge of the gas/liquid while the transfer device is being filled. Further, the discharge connector, which is used for connecting the gas/liquid transfer device to a hand held dispensing device, is configured to be tamper resistant.